If weren’t for giving up custody, borrowing against BTC in cases where you *could* pay in full makes clear financial sense.
1. If your ability to service the debt were to falter, you’d just pay off the loan.
2. If the interest on the loan is less than the rate of monetization of BTC, you’re going to come out ahead. (That is, you’ll have more Bitcoin remaining.)
It is the giving up of custody that makes it a non-starter for me.
